ARM Club 3/TheARMClub_PDCD3.iso/hensa/graphics/fracpaint_1/!FracPaint/Docs/Introduct

Text File | 1994-10-29 | 8KB | 180 lines

FracPaint is a powerful and flexible multi-tasking application to generate
fractal images. With FracPaint, more than thousand fractal formulas can be
used, together with a large number of parameters, to create an unlimited
number of images. Furthermore, colour maps can be used, to change the
appearance of an image.

Below, some basic principles of fractals and FracPaint will be explained.



Fractals
--------
FracPaint plots images of 'objects' (actually, sets of mathematical points)
that have fractal dimension. These objects are generated by relatively
simple calculations repeated over and over, feeding the results of each
step back into the next. FracPaint contains a lot of different formulas,
such as Mandelbrot and Lambda.

The objects with fractal dimension (known as fractals) are infinitely
complex; they reveal more and more detail without limit as you plot smaller
and smaller areas. FracPaint lets you 'zoom in' by dragging a rectangular
area at the image.

All image points which make the fractal object are known as 'inside'. All
other points are the 'outside'. The border between inside and outside gives
the most interesting images. FracPaint contains a number of methods to plot
inside and outside points.

Fractal images can be astonishingly beautiful, especially using screen
modes with lots of colours (256 colours in mode 15 or 28, or even more
colours with the new 15bpp or 24bpp RiscPC modes or a graphics enhancer
card). In addition, the image can be 'animated' by quickly shifting the
colour assignments (colour cycling). All colours within FracPaint are 24
bits.



Start up FracPaint
------------------
Double-click on the !FracPaint icon. FracPaint will install itself on the
icon bar. Click on the iconbar icon of FracPaint to create a new image
window. Sixteen of these image windows can be opened at the same time.

Click Menu on the iconbar icon to pop-up the main menu. Besides the usual
info and quit options, a dialogue box with speed information and a dialog
box with preferences can be opened.



Using FracPaint
---------------
All options of FracPaint can be changed through persistent dialogue boxes
(they will stay on the screen after a change). In this way, the effect of
an option can be determined very easily.

In all dialogue boxes the familiar RiscOS interface is used, like buttons
and writable fields. In addition FracPaint uses tab sheets. This is a new
component to make dialogue boxes more usable. For example, the Fractal and
Options dialogue boxes use these tab sheets. A tab sheet is a part of the
dialogue box with a corresponding label and name. A tab sheet can be
activated by clicking on the tab sheet label.



Zoom in
-------
Create a new image window by clicking on the FracPaint iconbar icon. Now
press the Select button at a corner of the zoom-box and move the mouse to
the opposite corner of the zoom-box. The zoom-box will be inverted on the
image. Release the mouse button, to start the calculation of the area
given by the zoom-box at full image size. Pressing Shift while dragging
the zoom-box will move the current zoom-box.



Mandel/Julia variant
--------------------
Most fractal formulas have two variants, the Mandel and Julia variants. The
Mandel variant uses a point of the image as c value in the formula with z0
as perturbation, and the Julia variant will use these variables the other
way round. So the Mandel and Julia variant use the same formula, but with
other start values. FracPaint will call these two formulas sisters.

To switch between the Mandel and Julia variant in FracPaint, click with
Adjust at an image window. The position will be used as perturbation values
if switched to the Julia variant. With Shift-adjust or with the menu option
Edit==>Sister, a new window will be created with the sister formula.



Fractal formulas
----------------
FracPaint contains a system of combined fractal formulas. This means that
the actual formula used to generate the image is constructed from a number
of different parts.

To change the current formula, open the fractal dialogue box with the menu
option Settings==>Fractal and select the Formula tab sheet. This tab sheet
contains the names of the current formula parts, together with a
description of the formula. Use the pop-up menu buttons beside the part
names to change the fractal formula.

In the description of the formula, the variable z is the calculated
variable. The variable pixel contains the values of the current point of
the image. The variables perturbation, fudge and bailout can be changed
using the Parameters tab sheet.



Load and save files
-------------------
FracPaint has it's own file type FracPars (&045) to load and store fractal
images. A FracPars file contains all parameters necessary to create the
fractal image (including it's colour map).

To save the image as a FracPars file, choose the menu option File=>Save. An
image can also be saved as a sprite file (sub-menu File=>Export). The
sprite file can be a mode 28 sprite with a 256 colour palette, or one of
the new Acorn 15 or 24-bits sprite formats.

To load a FracPars file, drag the file to the FracPaint iconbar icon. The
image will be generated in a new image window.



Undo/Redo
---------
Every zoom, parameter change and option change will be stored in an undo
buffer. Use the menu option Edit==>Undo, to go back one step (a maximum of
30 steps can be stored in the buffer). Use the menu option Edit==>Redo to
go forward one step.



Colour maps
-----------
A colour map is a file which defines 256 colours in a 24 bits format.
FracPaint uses colour maps to display the colours of a fractal image. For
example, a black-and-white colour map can be used for monochrome pictures
or a blue colour map can be used for a special effect.

To change the current colour map of an image, open the colour map dialogue
box with the menu option Settings==>Colour map.

The list of colour maps (in the pop-up menu of the colour map dialogue box)
will be build from the colour maps found in the path ColourMap$Path. Drag a
directory with colour maps to the colour map dialogue box, to add these
colour maps to the path and to the colour map list (with Shift-drag the
directory can be removed from the path). Another method to change the
colour map of an image is to drag a colour map file to an image window.

In the colour map dialogue box the offset of the inside and the outside can
also be changed. The offset is the colour of the colour map that will be
treated as colour 0.

Registered versions of FracPaint have also an Edit button, to see or change
the given colour map. The current colour map will be transported to a
colour map editor, from which it can be edited. Then, the colour map can be
saved to the image window again, to change the used colour map.



Colour cycling
--------------
With colour cycling, the image can be 'animated', by shifting all colours
of the colour map. Both the direction and speed of the colour cycling can
be set.

The colour cycle control window can be opened with the menu option
Utilities==>Colour cycle. This window has buttons to control the direction
and other colour cycle options. The step field controls the colour cycle
step size. Set this value to 2 with striped colour maps. Use the create
option, to create new colours (with the given number of shades) while
colour cycling. This will given very good results in 24bpp modes (and with
a large number of shades, say 16).

A processor with cache (ARM3 or later) and fast memory will give better
results with colour cycling.